The common causes of chronic cough are postnasal drip (also called upper airway cough syndrome), asthma, and reflux laryngitis / gastroesophageal reflux disease (GERD). These causes are responsible for up to 90 percent of all cases of chronic cough. Less common causes include infections, medications, and chronic lung diseases. Another common cause of chronic cough is nonasthmatic eosinophilic bronchitis. Following causes are usually considered for the chronic cough;
1) Upper airway cough syndrome; comprise of vasomotor rhinitis; acute nasopharyngitis; and sinusitis. The treatment is by steroid nasal spray or nasal antihistamine. Sinusitis may need antibiotics like trimethoprim-sulfamethoxazole or cefuroxime.
2) Cough variant asthma; will require bronchodilator medications used in asthma or steroid inhalers.
3) Reflux laryngitis and Gastroesophageal reflux disease (GERD); treatment is by avoidance of reflux-inducing foods (fatty foods, chocolate), eating five small meals a day without snacking, avoidance of meals for two to three hours before lying down (except for medications), the elevation of the head of the bed and an H2 antagonist or a proton pump inhibitor.
4) Postnasal drip; would need antihistamines and inhaled ipratropium bromide.
5) Non-specific cough; Dextromethorphan and/or codeine can be used.
The diagnostic and management protocol for chronic cough is as following;
1) we will do a chest x-ray first;
2) pulmonary function tests or spirometry is the second step
3) starting empiric therapy for postnasal drip, asthma, or gastroesophageal reflux. The GERD can be sometimes uncontrolled despite the medications and this will need further evaluation in the form of esophageal manometry (food pipe pressure study) and pH study of the food pipe (esophagus).
4) methacholine challenge testing to evaluate for airway hyperreactivity; done for the bronchospasm / bronchial asthma.
5) sputum or phlegm examination for eosinophils or empiric trial of corticosteroids for eosinophilic bronchitis.
If despite these measures, cough persists we would consider further investigations like esophagoscopy, 24-hour pH probe monitoring, high-resolution chest CT, or bronchoscopy.
I hope your symptoms resolve soon.
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